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41.
通过对应急响应手册2008版与2000版进行比较,找出2008版修订的内容,对于增加的内容进行了详细介绍。 相似文献
42.
43.
用过滤、XAD-8和XAD-4树脂串联吸附等方法将京密引水中的天然有机物定量分离为悬浮固体、憎水有机物、腐殖酸类化合物,XAD-4酸和其它亲水有机物。分别对不同形态有机物进行氯化处理,测定了产物中的挥发性卤代烃。结果表明,京密引水中天然有机物的主要挥发性氯化产物是氯仿,此外还生成一溴、二溴氯甲烷及少量溴仿。溶解态腐殖酸类化合物的悬浮固态和悬浮固态有机物是生成氯仿的最主要母体。亲水有机酸也具有较高的卤代活性,而其它有机成分则表现出相对惰性。 相似文献
44.
作为一种高效清洁的能源,燃气已经成为城市能源中的重要一员,燃气管网破坏亦成为城市所面临的重大安全隐患。城市埋地燃气管网的破坏风险,往往受到多种影响因素的共同作用。通过分析常州市埋地燃气管网破坏的影响因素,确定了地面沉降、地裂缝、城市内涝、土壤腐蚀等4个风险评价因子。运用MATLAB中的人工神经网络工具,通过人工神经网络计算,优化了模型网络结构,建立了常州市埋地燃气管网破坏风险预测的人工神经网络模型。分析计算结果,并为常州市埋地燃气管网的安全防护提供了建议。 相似文献
45.
Quantification and fractionation of mercury in soils from the Chatian mercury mining deposit,southwestern China 总被引:2,自引:0,他引:2
Contents of total Hg and Hg fraction, organic matter, pH, grain size and chemical composition were measured to investigate
the pollution characteristics and binding behavior of Hg in soils collected from the Chatian Hg mining deposit (CMD), southwestern
China. The average concentration of Hg concentration in the CMD soils was 155 and 1,315 times higher than that in control
soils and Chinese soils, respectively, suggesting that the CMD soils were heavily contaminated by the element. The finding
was confirmed by Müller geoaccumulation index assessment with 75% very seriously polluted, 6.25% highly to very highly polluted
and 18.75% moderately to highly polluted. Hg sources in the region were natural and anthropogenic: in addition to the pedogenic
process and original geochemical situation, human mining–refining activities have also seriously impacted the redistribution
of Hg in soils, especially in paddy soils. Based on the BCR protocol, soil Hg was divided into exchangeable (EXC), amorphous
Fe–Mn oxides (AFe–MnOX), organic-crystalline iron oxides (OM-CFe) and residual (RES) fraction. The average percentage of the
four fractions in the CMD followed the trend: RES (85.77%) > OM-CFe (12.44%) > AFe–MnOX (0.93%) ≥ EXC (0.86%), suggesting
that the majority proportion of soil Hg in the study area remained of residual form inside the soil mineral matrix. However,
their concentrations and percentages significantly varied among different locations and land use types. Soil physico-chemical
parameters were key factors affecting the presence of Hg fraction. Generally, Hg fraction concentrations were positively correlated
with the sand contents and soil pH values, which was presumably due to the basic anthropogenic input of Hg-containing materials
and their similarity to sand in physical characteristics. However, organic matter caused adsorption–fixation and reduction–volatilization
to coexist, which had opposite effects on Hg concentrations in soil, consequently exhibiting its dual nature. 相似文献
46.
47.
A pot experiment was conducted to investigate the dynamic changes in the rhizosphere properties and antioxidant enzyme responses of wheat plants (Triticum aestivum L.) grown in three levels of Hg-contaminated soils. The concentrations of soluble Hg and dissolved organic carbon (DOC) in the rhizosphere soil solutions of the wheat plants were characterised by the sequence before sowing > trefoil stage > stooling stage, whereas the soil solution pH was found to follow an opposite distribution pattern. The activities of antioxidant enzymes in wheat plants under Hg stress were substantially altered. Greater superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) activities were observed in the wheat plants grown in a highly polluted soil than in a slightly polluted soil (with increases of 11–27% at the trefoil stage and 26–70% at the stooling stage); however, increasing concentrations of Hg up to seriously polluted level led to reduced enzyme activities. The present results suggest that wheat plants could positively adapt to environmental Hg stress, with rhizosphere acidification, the enhancement of DOC production and greater antioxidant enzyme activities perhaps being three important mechanisms involved in the metal uptake/tolerance in the rhizospheres of wheat plants grown in Hg-contaminated soils. 相似文献
48.
石灰氮对镉污染土壤中镉生物有效性的影响 总被引:3,自引:0,他引:3
以石灰作对比,在大田条件下研究了不同石灰氮用量对镉污染土壤中镉生物有效性的影响。结果表明,一定量石灰或石灰氮处理均能显著提高酸性土壤的pH值,降低污染土壤中有效态镉质量分数及水稻茎叶和糙米中的镉质量分数。与不施改良剂的对照相比,石灰施用量达到1 200 kg.hm-2时土壤pH值显著提高,土壤有效态镉质量分数降低12.6%(P〈0.05),水稻茎叶和糙米中镉质量分数分别降低25.5%(P〈0.05)和28.3%(P〈0.05);石灰氮施用量达到600 kg.hm-2时,土壤pH值显著高于对照,土壤有效态镉质量分数较对照降低10.9%(P〈0.05),水稻茎叶和糙米中镉质量分数分别降低36.8%(P〈0.05)和33.0%(P〈0.05)。等量条件下(600 kg.hm-2)石灰氮对降低土壤镉有效性及水稻累积镉的效果相对优于石灰处理。因此,石灰氮与石灰一样可用于酸性重金属污染土壤的修复与改良,是一种极具潜力的土壤改良剂。 相似文献
49.
The ISCC technology representing an integrated solar combined cycle and the economic assessment of ISCC are investigated. Comparisons conducted by theoretical calculation method among two cases, that is, an integrated solar combined cycle system (ISCCS) and a combined cycle gas turbine system (CCGTS) show that ISCCS provides the best solution with the highest efficiency of heat to electricity among them. The results reflected by theoretical calculation also reveal that ISCCS is beneficial to energy saving and emission reduction. Due to the great advantages of ISCC, comprehensive analysis on the basic conditions for building ISCC power plants is analyzed in detail. 相似文献
50.